1. Field of the Invention
This invention relates generally to an apparatus for mixing cementitious materials, and more specifically, this invention relates to an auger type of mixing apparatus for quick-setting cementitious materials employing a volatile liquid.
2. Description of the Prior Art
Mixing apparatuses employing an elongated chute with an enclosed mixing auger or screw are known in the art. For example, one such apparatus is illustrated in U.S. Pat. No. 3,339,898--Futty et al., entitled "Mixing Method and Mixing Trough Construction", issued on Sept. 5, 1967 to Irl Daffin Associates, Incorporated.
IN structures of this type, the mixing auger is permanently mounted in the mixing trough. An elastomeric bottom member is positively secured to a frame. Access to the mixing chamber or trough is achieved through a door or doors on top of the apparatus.
In operation, the materials to be mixed are jointly inserted at an inlet, conveyed through the apparatus by the mixing auger and forced out the discharge opening at the other end of the mixing chamber.
One of the major drawbacks of a mixing apparatus of this type is that it is difficult to clean the inside of the mixing chamber. The limited access through the door or doors at the top of the chamber is not sufficient for complete cleaning of the auger mechanism and the inner chamber walls. While this problem is not insurmountable when utilized for conventional concrete, since the concrete does not completely harden for a long period of time and may be washed out with water, the problem becomes much more severe when the apparatus is utilized for a quick-setting cementitious material, such as that based upon the volatile liquid methyl methacrylate.
Another disadvantage of an apparatus of this type, when utilized for a quick-setting material employing a volatile liquid, is the lack of a complete seal. Thus, gaseous fumes released from the liquid, or the liquid itself, can escape from the mixing chamber. As such a liquid and its released gaseous fumes may be hazardous, prior art mixing apparatuses cannot be safely used.
Since differing volatile liquids might be involved, an elastomeric trough bottom suitable for one material might react with another material and be completely unsuitable. Therefore, even if a prior art mixing apparatus could be modified to permit its utilization with a quick-setting cementitious material, the elastomeric material utilized may render it unsuitable for a particular quick-setting cementitious material.
Accordingly, it would be desirable to provide a mixing apparatus for a cementitious material employing a volatile liquid that would not permit the escape of the volatile liquid or its vaporized fumes from the mixing chamber. Also, such an apparatus should be readily adaptable for various types of cementitious materials based on different volatile liquids or active components. Further, the apparatus should be constructed so that it may be easily and quickly cleaned after the mixing operation has ceased.